Ultrabroad terahertz bandpass filter by hyperbolic metamaterial waveguide

Area of Science:

• Metamaterials
• Terahertz (THz) Photonics
• Waveguide Technology

Background:

• Terahertz (THz) technology requires efficient bandpass filters for various applications.
• Existing THz filters often face limitations in bandwidth, polarization dependence, or sharp transitions.

Purpose of the Study:

• To propose and numerically demonstrate an ultrabroad terahertz bandpass filter (BPF).
• To achieve wide passband operation and polarization independence using integrated hyperbolic metamaterial (HMM) waveguides.

Main Methods:

• Integration of two different-sized tapered hyperbolic metamaterial (HMM) waveguides into a unit cell.
• Numerical simulation and structural design to control absorption and transmission bands of HMM waveguides.
• Analysis of transmission spectrum, bandwidth, bandedge transitions, and polarization dependence.

Main Results:

• Demonstration of an ultrabroad THz BPF with a broad passband.
• Achieved peak transmission of 37% at 3.3 THz with a bandwidth of 2.2 THz (2.97–5.17 THz) for TM-polarized light.
• Exhibited polarization independence due to structural symmetry and sharp bandedge transitions (22.6 and 17.6 dB/THz).

Conclusions:

• The designed HMM BPF shows significant potential for practical THz applications.
• The proposed structure offers a promising approach for developing versatile THz filters with ultrabroad bandwidth and polarization independence.